'Big Dry' claims River Murray lakes

After seven years of drought, flooding with seawater may be river system's only hope
Barbara McMahon, The Observer 10 Aug 08;

Australia's epic drought is tightening its grip as a deepening ecological crisis unfolds in the south of the country. After seven years of the Big Dry, water levels in lakes at the mouth of the mighty Murray river have fallen by up to 50cm below sea level and environmental damage is spreading on a massive scale, according to conservationists.

At Bottle Bend Lagoon, drought and over-use of water by farmers for irrigation has left swaths of riverbed exposed, producing a toxic chemical reaction that is spreading. The banks are lined with poisonous aluminium and manganese salts and the water is dun-coloured, smells like rotten eggs and is as corrosive as battery acid. Fish have died in their thousands and red gum trees and plants are also dying.

The same environmental disaster is happening in nearby Lakes Albert and Alexandrina, internationally recognised wetlands that are home to a wide range of migratory birds. Australia's water minister, Penny Wong, has said the lakes may be beyond salvation. But she dismissed calls for more fresh water to be allowed to flow down the Murray - the river is controlled by dams, weirs and locks - saying dwindling supplies were needed for essential human demands.

Now, a controversial option of flooding the area with seawater is being considered. Professor Tim Flannery, Australia's best-known climate-change commentator, said that the action would be 'risky and probably unpopular', but that it could help save the dying eco-system by preventing the exposed lake bed from turning irreversibly acidic and toxic. A weir would be constructed to prevent salt or acidic water contaminating Adelaide's drinking water supply.

Peter Cosier, of the pressure group Concerned Scientists, is leading the opposition to the plan, saying it would alter the ecosystem beyond recognition. 'The advice I have is that, once the salt water's in there, it's next to impossible to get out,' he said.

The Murray Darling Basin Commission manages the vast river system that provides water to Australia's 'food bowl', a vast expanse of land that runs down the continent's eastern coast. It is studying options for the endangered lakes and is due to report to ministers on the seawater plan by October.

The crisis has come about because Australia is in the grip of the worst drought in a century. Years of scant rainfall have left vast areas parched and last month it was predicted that up to a million people could face a shortage of drinking water if the drought continues. The report from government officials warned that there could be problems supplying drinking water from the Murray Darling in 2008-2009 unless there is significant rainfall soon.

Another report by scientists predicted that Australasia would experience a tenfold increase in heatwaves as a result of climate change. Exceptionally hot years, which used to occur once every 22 years, would come every one or two years, making drought a part of the landscape. Water in public storage in the basin is at only 21 per cent capacity.

Arlene Buchan, director of the Australian Conservation Foundation, said the lakes need 300 to 400 gigalitres of water - a gigalitre is equivalent to 1,000 Olympic-sized swimming pools - before the year's end. 'Unless we get that water, we are facing an ecological disaster.'